Multiple input multiple output (MIMO) systems are wireless communications systems that are specified in, for example, resolution 802.11n from the Institute of Electrical and Electronics Engineers (IEEE). A MIMO system that receives a signal Y may compute a channel estimate matrix, H, based on the received signal. The signal may comprise information generated from a plurality of information sources. A transmitting MIMO system may utilize a plurality of transmitting antennas when transmitting the signal Y. A receiving MIMO system may utilize a plurality of receiving antennas when receiving the signal Y. The channel estimate matrix for a downlink RF channel, Hdown, may describe a characteristic of the wireless transmission medium in the transmission path from a transmitter, to a receiver. The channel estimate for an uplink RF channel, Hup may describe a characteristic of the wireless transmission medium in the transmission path from the receiver to the transmitter. According to the principle of reciprocity, a characteristic of the wireless transmission medium in the transmission path from the transmitter to the receiver may be assumed to be identical to a corresponding characteristic of the wireless transmission medium in the transmission path from the receiver to the transmitter.
When the transmitter and receiver are MIMO systems, corresponding beamforming matrices may be configured and utilized for transmitting and/or receiving signals based on the characteristic channel estimate matrix H. Beamforming is a method for signal processing that may allow a transmitting MIMO system to combine a plurality of signals in a transmitted signal Y. Beamforming is also a method for signal processing that may allow a receiving MMO system to separate individual signals in a received signal Y.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.